Conventionally, radio frequency detection systems and methods use active circuits to detect nearby radio frequency emissions. Such conventional systems and methods require power supplies and amplifiers in addition to other circuitry such as diodes, capacitors, etc. for detection and indication. Disadvantageously, these conventional systems and methods always require a power supply, which for handheld or mobile applications, typically requires batteries that must be recharged or replaced. The requirement for an active source for the conventional systems and methods is inconvenient, impractical, and sometimes unreliable.